Due to the feature that a foldable chair is portable and foldable, not only can the movement be facilitated, but also the space is saved. Therefore, the foldable chair is widely used at places such as various training organizations, schools at all levels, public places, hospitals, restaurants, hotels, companies and families. A commonly seen foldable chair comprises a chair frame, a chair seat and a chair backrest and can be folded on the whole.
Taking a beach chair frame disclosed with publication number CN201480624 as an example, referring to FIG. 1, the beach chair frame comprises a left backrest pipe 11′, a right backrest pipe 12′, a left seat cushion pipe 21′, a right seat cushion pipe 22′, a left armrest pipe 31′, a right armrest pipe 32′, a left rear leg pipe 41′, a right rear leg pipe 42′ and rear cross pipes 5′, wherein front portions of the left seat cushion pipe 21′ and the right seat cushion pipe 22′ are movably connected with upper portions of the left armrest pipe 31′ and the right armrest pipe 32′, rear portions of the left seat cushion pipe 21′ and the right seat cushion pipe 22′ are movably connected with the left rear leg pipe 41′ and the right rear leg pipe 42′, the middle-rear portions of the left seat cushion pipe 21′ and the right seat cushion pipe 22′ are movably connected with the left backrest pipe 11′ and the right backrest pipe 12′, bottom portions of the left armrest pipe 31′ and the right armrest pipe 32′ are movably connected with bottom portions of the right backrest pipe 12′ and the left backrest pipe 11′, a middle portion of the left armrest pipe 31′ is crossly and movably connected with a middle portion of the right armrest pipe 32′, top portions of the left rear leg pipe 41′ and the right rear leg pipe 42′ are movably connected with the left backrest pipe 11′ and the right backrest pipe 12′, a left sliding sleeve 61′ and a right sliding sleeve 62′ are arranged at connecting positions, the left sliding sleeve 61′ and the right sliding sleeve 62′ are nested in the left backrest pipe 11′ and the right backrest pipe 12′, and armrest limiting sleeves 71′ and 72′ are arranged at upper portions of the left sliding sleeve and the right sliding sleeve. Bottom portions of the left rear leg pipe 41′ and the right rear leg pipe 42′ are respectively and movably connected with the bottom portions of the left and right sides of the rear cross pipes, and the top portions of the left and right sides of the rear cross pipes are respectively and movably connected with the left and right backrest pipes. By adopting movable connecting structures at connecting positions between components, the beach chair frame can be unfolded and folded.
For the foldable chair frame structure with the above-mentioned structure, since the backrest pipes are fixed and are simultaneously used as front supporting legs to form front leg pipes, the backrest pipes and the front leg pipes are integral, the upper portions used as a backrest can only be in parallel with the supporting leg portions below and a certain inclination angle needs to be kept, the elevation angle of the backrest is a certain fixed angle, the effect of comfortably resting on the backrest cannot be achieved and the sitting comfortableness of the foldable chair frame is not good.